Home parenteral nutrition is now available to provide long term nutritional support for individuals who can no longer maintain their health and well-being in the usual oral manner. It is the broad objective of the proposed research to determine the intravenous nutritional requirements capable of promoting an optimum nutritional state in patients who rely completely on long term parenteral nutrition. The secondary objective is to develop a way in which to supply these requirements within an 8-hour period per day, thus allowing patients to be off infusion as much as possible. The areas to be investigated include: 1. The partial isocaloric substitution of fat or alcohol for glucose on a chronic basis to determine if it is a safe manner in which to supply the total daily caloric requirements within 8 hours per day. 2. The determination of the daily intravenous requirements of trace metals and essential fatty acids.